Preheat oven to 350F. Line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large bowl with an electric mixer, beat the softened butter and sugar on medium-high speed until light and fluffy, about 3 minutes. Scrape down the bowl as needed.

Beat in the egg, vanilla, and almond extract until fully combined, about 1 minute. The mixture should look smooth and pale.

With the mixer on low speed, gradually add the flour mixture. Mix just until no dry streaks remain - do not overmix.

Using a rubber spatula, gently fold in the rainbow sprinkles until evenly distributed throughout the dough.

Scoop dough into 1.5 tablespoon balls. Roll between your palms for smooth rounds, then roll in coarse sugar or extra sprinkles if desired. Place 2 inches apart on prepared sheets. Bake until the edges are set and just beginning to turn golden but centers still look slightly underdone, 10 to 12 minutes.

Let cookies rest on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely. They will firm up as they cool.